Method and system for surgical navigation

ABSTRACT

A surgical navigation method includes obtaining a three-dimensional image; selecting a viewing angle direction; generating one or more two-dimensional images arranged along the viewing angle direction from the three-dimensional image; superimposing the one or more two-dimensional images along the viewing angle direction to form a two-dimensional superimposed image; and guiding a movement of a virtual surgical instrument into the two-dimensional superimposed image.

RELATED APPLICATIONS

This application is a Continuation-in-part of U.S. application Ser. No.17/389,747, filed on Jul. 30, 2021, which is herein incorporated byreference.

BACKGROUND Technical Field

The present invention generally relates to methods and systems forsurgical navigation, and in particular, methods and systems relating tothe manipulation of radiographic imagery to provide a more efficient andaccurate method for directing surgical tools.

Description of Related Art

Surgical navigational methods and systems help medical staff locate bodyparts of a patient (such as, e.g., osseous and soft tissue structures)and guide and place medical surgical instruments, and can performimplant placement surgery (such as, e.g., screws, pins, cages, graftmaterials, etc.) into the body parts. Surgeons may use utilizeradiographic images, such as an X-ray scan or a computed tomography (CT)scan, to help locate certain targets in a patient's body. For example,in a case involving the placement of a screw into a patient's spine or acage into a patient's sacroiliac joint, a surgeon may observe an X-rayimage of the patient's spine to help guide the correct placement of thescrew. However, there are deficiencies with such conventional surgicalnavigation systems. For example, whether using X-ray or CT imagery,certain anatomical structures (such as a pedicle on a patient's spine, asacroiliac joint, etc.) may be difficult to locate, which may lead toextra time in the operating room to correctly place surgicalinstruments. In turn, extended time in the operating room can lead tocomplications with anesthesia, a greater risk developing an infection,higher risk for developing a blood clot, and an overall poorer patientoutcome. Additionally, difficulty in locating correct anatomicalstructures may lead to errors in surgical instrument placement. This canresult in the need for additional corrective surgeries.

In an attempt to address these deficiencies, surgeons and other medicalpersonnel have resorted to obtaining additional radiographic scans inhopes of obtaining a clearer view of the desired anatomical structure.This approach, however, can be time consuming and result in additionalfinancial costs. Additionally, this approach requires the patient tosubmit to multiple radiographic scanning procedures, which may harm thepatient by increasing the patient's lifetime X-ray exposure (causing anincreased risk for developing cancers).

In view of the foregoing, it is desirable to reduce the time andincrease the accuracy of identifying anatomical structures in surgicalpatients. For example, there is a need for an improved method and systemto utilize imagery that can more consistently and reliably identifyanatomical structures.

SUMMARY

According to one aspect of the present disclosure, a surgical navigationmethod includes obtaining a three-dimensional image; selecting a viewingangle direction; generating one or more two-dimensional images arrangedalong the viewing angle direction from the three-dimensional image;superimposing the one or more two-dimensional images along the viewingangle direction to form a two-dimensional superimposed image; andguiding a movement of a virtual surgical instrument into thetwo-dimensional superimposed image.

According to another aspect of the present disclosure, a surgicalnavigation system includes a memory, a controller and a display device.The memory is configured to store a three-dimensional image. Thecontroller is configured to select a viewing angle direction accordingto an instruction; generate one or more two-dimensional images arrangedalong the viewing angle direction from the three-dimensional image;superimpose the one or more two-dimensional images along the viewingangle direction to form a two-dimensional superimposed image; and guidea virtual surgical instrument into the two-dimensional superimposedimage. The display device is configured to display the two-dimensionalsuperimposed image.

According to further another aspect of the present disclosure, acomputer-readable storage medium includes instructions, which whenexecuted on a processor causes the processor to perform a surgicalnavigational method, the surgical navigational method includes obtaininga three-dimensional image; selecting a viewing angle direction accordingto an instruction; generating one or more two-dimensional imagesarranged along the viewing angle direction from the three-dimensionalimage; superimposing the two-dimensional images along the viewing angledirection to form a two-dimensional superimposed image; and guiding amovement of a virtual surgical instrument into the two-dimensionalsuperimposed image.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate various embodiments and aspects ofthe present disclosure. In the drawings:

FIG. 1 is a schematic flowchart illustrating a surgical navigationmethod according to the 1st embodiment of the present disclosure.

FIG. 2 is a schematic flowchart illustrating a surgical navigationmethod according to the 2nd embodiment of the present disclosure.

FIG. 3 is a schematic diagram illustrating the guiding of a virtualsurgical instrument using the surgical navigation method of FIG. 2 .

FIG. 4 is a schematic diagram illustrating superimposition at a spinalsegment location corresponding to an image superimposing step of thesurgical navigation method of FIG. 2 .

FIG. 5 is a schematic diagram illustrating a superimposed image in afirst viewing direction generated in the surgical navigation method ofFIG. 2 .

FIG. 6 is a schematic diagram illustrating a superimposed image in asecond viewing direction generated in the surgical navigation method ofFIG. 2 .

FIG. 7 is a schematic diagram illustrating a surgical navigation systemaccording to the 3rd embodiment of the present disclosure.

FIG. 8 is a schematic flowchart illustrating a surgical navigationmethod according to the 4th embodiment of the present disclosure.

FIG. 9 is a schematic flowchart illustrating a surgical navigationmethod according to the 5th embodiment of the present disclosure.

FIG. 10 is a schematic diagram illustrating the guiding of a virtualsurgical instrument using the surgical navigation method of FIG. 9 .

FIG. 11 is a schematic diagram illustrating superimposition oftwo-dimensional images in an image superimposing step of the surgicalnavigation method of FIG. 9 .

FIG. 12 is a schematic diagram illustrating selection of a first viewingangle direction in a viewing angle direction selecting step of thesurgical navigation method of FIG. 9 .

FIG. 13 is a schematic diagram illustrating the selection of the firstviewing angle direction continued from FIG. 12 .

FIG. 14 is a schematic diagram illustrating two-dimensional superimposedimages in the surgical navigation method of FIG. 9 .

FIG. 15 is a schematic diagram illustrating another two-dimensionalsuperimposed image in the surgical navigation method of FIG. 9 .

FIG. 16 is a schematic diagram illustrating a surgical navigation systemaccording to the 6th embodiment of the present disclosure.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings.Wherever possible, the same reference numbers are used in the drawingsand in the following description to refer to the same or similar parts.While several exemplary embodiments and features of the invention aredescribed herein, modifications, adaptations, and other implementationsare possible without departing from the spirit and scope of theinvention. For example, substitutions, additions, or modifications maybe made to the components illustrated in the drawings, and the exemplarymethods described herein may be modified by substituting, reordering, oradding steps to the disclosed methods. Accordingly, the followingdetailed description does not limit the invention. Instead, the properscope of the invention is defined by the appended claims.

In addition, when a component (or apparatus or module, etc.) is“connected/linked to” another component, it may mean that the componentis directly connected/linked to the another component, or it may meanthat a certain component is indirectly connected/linked to anothercomponent, i.e., there are other components between the component andthe another component. When it is clearly stated that a certaincomponent is “directly connected/linked” to another component, it meansthat there is no other component between the component and the anothercomponent. The terms “first”, “second”, “third”, etc. are only used todescribe different components, and there are no restrictions on thecomponents themselves. Therefore, the first component may also berenamed the second component. In addition, a combination ofcomponents/apparatuses/circuits herein is not a commonly known,conventional or well-known combination in the art. Whethercomponents/units/circuits themselves are well-known cannot be used todetermine whether the combination relationship thereof is easilycompleted by a person of ordinary skill in the art.

FIG. 1 is a schematic flowchart illustrating a surgical navigationmethod 100 according to the 1st embodiment of the present disclosure.The surgical navigation method 100 is used for guiding a virtualsurgical instrument and includes an image reading step S02, an imageadjusting step S04, an image superimposing step S06, and an instrumentguiding step S08.

In accordance with some embodiments of the present disclosure, the imagereading step S02 includes reading a three-dimensional image (such as,e.g., an image of a spine), from a memory. The three-dimensional imageincludes one or more two-dimensional images, and the two-dimensionalimages may be obtained through scanning along at least one cuttingdirection. In accordance with some embodiments, the image adjusting stepS04 includes selecting a part or portion of one or more of the selectedtwo-dimensional spinal images along at least one viewing angledirection, where the part of the two-dimensional spinal images containsa three-dimensional pedicle region.

In accordance with some embodiments of the present disclosure, the imagesuperimposing step S06 includes superimposing the selected part of thetwo-dimensional spinal images (along the at least one viewing angledirection) to form a superimposed viewing direction image. Thesuperimposed viewing direction image presents at least onetwo-dimensional superimposed region according to the at least oneviewing angle direction, and the at least one two-dimensionalsuperimposed region corresponds to the three-dimensional pedicle region.

In accordance with some embodiments of the present disclosure, theinstrument guiding step S08 includes real time rendering the virtualsurgical instrument in the at least one two-dimensional superimposedregion of the superimposed viewing direction image according to theposition of the surgical instrument. Therefore, according to thesurgical navigation method 100, two-dimensional spinal images aresuperimposed and presented in a specific range. In accordance with someembodiments, utilizing this superimposed viewing direction image helpsdistinguish a pedicle contour because the outer layer of the pedicle isof high density bone and high density bone appears bright white in theimage. Depending on the viewing angle direction chosen, a coronal planecontour, a sagittal plane contour or an axial plane contour of pediclecan be clearly identified in the image allowing for efficientapplication of a CBT screw implantation technique. Medical staff maycorrectly fix a screw in the pedicle using the superimposed viewingdirection image and can greatly shorten the time for medical staff tofind and determine an implantation position and path, thereby improvingsafety and patient outcomes. The following description provides detailedembodiments to illustrate the details of the above steps.

FIG. 2 is a schematic flowchart illustrating a surgical navigationmethod 100 a according to the 2nd embodiment of the present disclosure.FIG. 3 is a schematic diagram illustrating the guiding of a surgicalinstrument 512 by using the surgical navigation method 100 a of FIG. 2 .FIG. 4 is a schematic diagram illustrating the superimposing at a spinalsegment in an image superimposing step S16 of the surgical navigationmethod 100 a of FIG. 2 . FIG. 5 is a schematic diagram illustrating asuperimposed viewing direction image 130 of the surgical navigationmethod 100 a of FIG. 2 . FIG. 6 is a schematic diagram illustratinganother superimposed viewing direction image 130 a of the surgicalnavigation method 100 a of FIG. 2 .

In accordance with some embodiments of the present disclosure, thesurgical navigation method 100 a is used for guiding a virtual surgicalinstrument. The virtual surgical instrument may correspond to onesurgical instrument 512 and may be displayed for the surgeon. Thesurgical navigation method 100 a includes an image reading step S12, animage adjusting step S14, an image superimposing step S16, asuperimposing adjustment step S17, and an instrument guiding step 518.In accordance with some embodiments, the image reading step S12, theimage adjusting step S14, the image superimposing step S16, thesuperimposing adjustment step S17, and the instrument guiding step S18may be applied in conjunction with a cortical bone trajectory (CBT)screw implantation technique where the virtual surgical instrument is avirtual screw, and the surgical instrument 512 is a screw. However,other virtual surgical instruments and surgical instruments 512 may beused.

In accordance with some embodiments of the present disclosure, the imagereading step S12 includes reading a three-dimensional spinal image 110from a memory, where the three-dimensional spinal image 110 includestwo-dimensional spinal images 120, and the two-dimensional spinal images120 are obtained through scanning along at least one cutting directionD1. In accordance with some embodiments, the three-dimensional spinalimage 110 is a three-dimensional medical image generated throughscanning of the spine by CT and reconstruction. During CT scanning,specific scanning parameters are used to obtain a required image. Thescanning parameters include a layer thickness and a spacing, where thelayer thickness denotes a section thickness of each two-dimensionalspinal image 120, and the spacing denotes a distance between twoadjacent two-dimensional spinal images 120. In other words, eachtwo-dimensional spinal image 120 has a layer thickness, and there is aspacing between adjacent two of the two-dimensional spinal images 120.

In accordance with some embodiments of the present disclosure, the imageadjusting step S14 includes selecting a part 120P of one or more of thetwo-dimensional spinal images 120 along at least one viewing angledirection D2, where the part 120P of the one or more two-dimensionalspinal images 120 contains a three-dimensional pedicle region R_(3D). Inaccordance with some embodiments, the image adjusting step S14 includesa target point selection step S142, a viewing angle direction selectionstep S144, and a region selection step S146, where the target pointselection step S142 includes selecting a target point TP from thetwo-dimensional spinal images 120. The viewing angle direction selectionstep S144 includes selecting the at least one viewing angle direction D2according to the two-dimensional spinal images 120. The region selectionstep S146 is to select the part 120P of the two-dimensional spinalimages 120 along the at least one viewing angle direction D2 for thetarget point TP of the two-dimensional spinal images 120, where the part120P of the two-dimensional spinal images 120 contains athree-dimensional pedicle region R_(3D). Furthermore, thethree-dimensional pedicle region R_(3D) is columnar and has a pediclelength L, a pedicle width W, and a pedicle height H. The target point TPis close to the three-dimensional pedicle region R3D.

In accordance with some embodiments of the present disclosure, the imagesuperimposing step S16 includes superimposing the part 120P of thetwo-dimensional spinal images 120 along the at least one viewing angledirection D2 to form a superimposed viewing direction image 130, wherethe superimposed viewing direction image 130 presents at least onetwo-dimensional superimposed region (such as R_(2D_1) in FIG. 4 andR_(2D_1), R_(2D_2) and R_(2D_3) in FIGS. 5 and 6 ) according to the atleast one viewing angle direction D2, and the at least onetwo-dimensional superimposed region corresponds to the three-dimensionalpedicle region R_(3D).

In accordance with embodiments of the present disclosure, the imagesuperimposing step S16 is advantageous because high bone density regionsappear white in a CT image, and because the pedicle surface density ishigh. Thus, the two-dimensional superimposed region corresponding to thethree-dimensional pedicle region R_(3D) can clearly identify the whitepedicle contour in the picture. Additionally, different viewing angledirections D2, may generate different superimposed viewing directionimages 130 and corresponding two-dimensional superimposed regions, suchas a coronal plane contour, a sagittal plane contour or an axial planecontour of pedicle. In accordance with some embodiments, the number ofthe viewing angle directions D2 is the same as that of thetwo-dimensional superimposed regions and the number may be plural, andthe viewing angle directions D2 may include (but not limited to) a firstviewing angle direction, a second viewing angle direction, and a thirdviewing angle direction. The two-dimensional superimposed regions mayinclude (but not limited to) a first two-dimensional superimposed regionR_(2D_1), a second two-dimensional superimposed region R_(2D_2), and athird two-dimensional superimposed region R_(2D_3). The superimposedviewing direction image 130 may include (but not limited to) asuperimposed coronal plane 132, a superimposed sagittal plane 134, and asuperimposed axial plane 136. The target point TP is close to the firsttwo-dimensional superimposed region R_(2D_1), the second two-dimensionalsuperimposed region R_(2D_2), and the third two-dimensional superimposedregion R_(2D_3).

In accordance with some embodiments of the present disclosure, thesuperimposed coronal plane 132 has a two-dimensional coronal coordinatesystem, where the superimposed coronal plane 132 presents one or twofirst two-dimensional superimposed regions R_(2D_1) according to thethree-dimensional pedicle region R_(3D) in the first viewing angledirection, and each first two-dimensional superimposed region R2D_1 hasa pedicle height H, a pedicle width W, and a closed contour. The closedcontour is the coronal plane contour of pedicle.

In accordance with some embodiments of the present disclosure, thesuperimposed sagittal plane 134 has a two-dimensional sagittalcoordinate system, where the superimposed sagittal plane 134 presentsone second two-dimensional superimposed region R_(2D_2) according to thethree-dimensional pedicle region R_(3D) in the second viewing angledirection, and the second two-dimensional superimposed region R_(2D_2)has a pedicle length L, a pedicle height H, and a sagittal plane contourof pedicle.

In accordance with some embodiments of the present disclosure, thesuperimposed axial plane 136 has a two-dimensional abscissa system,where the superimposed axial plane 136 presents one or two thirdtwo-dimensional superimposed regions R_(2D_3) according to thethree-dimensional pedicle region R_(3D) in the third viewing angledirection, and each third two-dimensional superimposed region R_(2D_3)has the pedicle length L, the pedicle width W, and an axial planecontour of pedicle. After the image superimposing step S16, the pediclecontour of the spinal segment corresponding to the target point TP inthe superimposed viewing direction image 130 is the clearest.

In accordance with some embodiments of the present disclosure, thesuperimposing adjustment step S17 includes adjusting the number of theparts 120P of the two-dimensional spinal images 120 superimposed alongat least one viewing angle direction D2 according to a contour sharpnessof the two-dimensional superimposed regions in the superimposed viewingdirection image 130.

In accordance with some embodiments of the present disclosure, theinstrument guiding step S18 includes real-time rendering the virtualsurgical instrument in the two-dimensional superimposed region of thesuperimposed viewing direction image 130 according to the position ofthe surgical instrument.

As shown in FIG. 4 , in some embodiments, the viewing angle direction D2of the superimposed coronal plane 132 may be the first viewing angledirection. In accordance with some embodiments, three-dimensional spinalimages 110 generated by the CT scanning of one spinal segment along thecutting direction D1 corresponding to the first viewing angle directioninclude two-dimensional spinal images 120, and the part 120P of thesetwo-dimensional spinal images 120 contains the three-dimensional pedicleregion R_(3D).

The two-dimensional spinal images 120 are superimposed to form asuperimposed coronal plane 132. The superimposed coronal plane 132presents one or two first two-dimensional superimposed regions R_(2D_1)according to the three-dimensional pedicle region R_(3D) in the firstviewing angle direction.

In some embodiments, as shown in FIG. 5 and FIG. 6 , the viewing angledirection D2 of the superimposed sagittal plane 134 may be the secondviewing angle direction. In accordance with some embodiments,three-dimensional spinal images 110 generated by the CT scanning of aplurality of spinal segments along the cutting direction D1corresponding to the second viewing angle direction includetwo-dimensional spinal images, and the part of these two-dimensionalspinal images covers the three-dimensional pedicle region R_(3D).

The two-dimensional spinal images superimposed along the direction ofthe pedicle width W (i.e., the second viewing angle direction of theviewing angle direction D2), to form a superimposed sagittal plane 134.The superimposed sagittal plane 134 presents one or two secondtwo-dimensional superimposed region R_(2D_2) according to thethree-dimensional pedicle region R_(3D) in the second viewing angledirection.

In accordance with some embodiments of the present disclosure, as shownin FIG. 5 and FIG. 6 , the viewing angle direction D2 of thesuperimposed axial plane 136 may be the third viewing angle direction.In accordance with some embodiments, three-dimensional spinal images 110generated by the CT scanning of one spinal segment along the cuttingdirection D1 corresponding to the third viewing angle direction includetwo-dimensional spinal images, and the part of these two-dimensionalspinal images contains the three-dimensional pedicle region R_(3D).

The two-dimensional spinal images superimposed along the direction ofthe pedicle height H (i.e., the third viewing angle direction of theviewing angle direction D2), to form a superimposed axial plane 136. Thesuperimposed axial plane 136 presents one or two third two-dimensionalsuperimposed region R_(2D_3) according to the three-dimensional pedicleregion R_(3D) in the third viewing angle direction.

There is no correlation between the operations of adjusting andsuperimposing images of FIG. 5 and FIG. 6 . This means that theadjusting and superimposing images of FIG. 5 and FIG. 6 can be performedindependently, such that medical staff can clearly understand therelative positions of the three-dimensional pedicle region R_(3D) indifferent viewing angles.

In other embodiments, the number, layer thickness T and spacing S of thetwo-dimensional spinal image 120 of the three-dimensional spinal image110, and the pedicle length L, pedicle width W, pedicle height H,cutting direction D1, viewing angle direction D2 and position of thetarget point TP of the three-dimensional pedicle region R3D can bechanged according to actual conditions or demands, and the presentdisclosure is not limited to the above.

In accordance with embodiments of the present disclosure, only the part120P of the two-dimensional spinal images 120 is superimposed in thepresent disclosure, which has a clearer local contour, compared with thefull display of the two-dimensional spinal images 120 that wouldotherwise make it harder to focus on the point of interest.

FIG. 7 is a schematic diagram illustrating a surgical navigation system200 according to the 3rd embodiment of the present disclosure. Thesurgical navigation system 200 is configured to guide a virtual surgicalinstrument 140 and includes a memory 300, a processor 400, an instrumentmodule 510, a spine optical sensing apparatus 520, an optical tracker600, and a display device 700.

Although not shown, the various components of surgical navigation system200 need not be fully contained within the user device. Each of thecomponents may be physically separated from another and more than one ofthe components may be used to perform methods consistent with thepresent disclosure. Even though the components may be physicallyseparated, the components may still be communicably connected by meansof wired or wireless technology. For example, different components ofsystem 100 and user device may be connected through the Internet, a LAN(local area network), a WAN (wide area network), databases, servers, RF(radio frequency) signals, cellular technology, Ethernet, telephone,“TCP/IP” (transmission control protocol/internet protocol), and anyother electronic communication format.

In accordance with some embodiments of the present disclosure, thememory 300 is configured to access a three-dimensional spinal image 110,where the three-dimensional spinal image 110 includes one or moretwo-dimensional spinal images 120, and the two-dimensional spinal images120 are obtained through scanning along at least one cutting directionD1. The memory 300 may include all forms of computer-readable storagemediums such as non-volatile or volatile memories including, by way ofexample, semiconductor memory devices, such as EPROM, RAM, ROM, DRAM,EEPROM, and flash memory devices; magnetic disks such as internal harddisks and removable disks; magneto-optical disks; DVD disks, and CD-ROMdisks. Memory device 300 may be used to store program code.

In accordance with some embodiments of the present disclosure, theprocessor 400 is electrically connected to the memory 300, where thecomputing processing apparatus 400 receives the three-dimensional spinalimage 110 and is configured to perform operations including thefollowing steps: an image reading step S02/S12, an image adjusting stepS04/S14, an image superimposing step S06/S16, a superimposing adjustmentstep S17, and an instrument guiding step S08/S18 described above andshown in FIG. 1 to FIG. 6 .

In accordance with some embodiments of the present disclosure, theprocessor 400 may be an ASIC (Application Specific Integrated Circuit)or it may be a general purpose processor. The processor 400 may includemore than one processor. For example, processors may be situated inparallel, series, or both in order to process all or part of thecomputer instructions that are to be processed.

In accordance with some embodiments of the present disclosure, theinstrument module 510 includes a surgical instrument 512 and a surgicalinstrument optical sensing apparatus 514, where the surgical instrument512 is controlled and displaced by medical staff. The surgicalinstrument optical sensing apparatus 514 may be disposed on the surgicalinstrument 512, and includes a reflective ball and a fixing frame, andthe fixing frame may be located between the reflective ball and thesurgical instrument 512. The surgical instrument 512 may be a CBT screw,a guide probe or another surgical instrument, depending on the selectionof medical staff and use conditions. The spine optical sensing apparatus520 may be disposed on a spine 530 and includes a reflective ball and afixing frame. The fixing frame may be located between the reflectiveball and the spine 530. The optical tracker 600 may be electricallyconnected to the processor 400 and configured to track the spine 530 andthe surgical instrument 512. When the medical staff control the surgicalinstrument 512, the surgical instrument optical sensing apparatus 514may be facing to the optical tracker 600, so that the optical tracker600 can track the surgical instrument 512 in real time. In addition, thespine optical sensing apparatus 520 may also be facing to the opticaltracker 600, so that the optical tracker 600 can track the spine 530 inreal time.

In accordance with some embodiments of the present disclosure, thedisplay device 700 may be electrically connected to the processor 400,and displays a screen picture, and the screen picture presents thesuperimposed coronal plane 132, the superimposed sagittal plane 134, thesuperimposed axial plane 136 or the virtual surgical instrument 140 ofthe superimposed viewing direction image 130/130 a. The display device700 may be any conventional user interface display device. For example,display device 700 may include computer monitors, televisions, and LCDdisplays. Display device 700 may display GUI (Graphical User Interface)which allows a user to interact with system 200 hardware and softwareapplications.

FIG. 8 is a schematic flowchart illustrating a surgical navigationmethod 40 according to the 4th embodiment of the present disclosure. Thesurgical navigation method 40 of the 4th embodiment is used for guidinga virtual surgical instrument and includes an image obtaining step S41,a viewing angle direction selecting step S43, an image generating stepS45, an image superimposing step S46, and an instrument guiding stepS48.

In accordance with some embodiments of the present disclosure, the imageobtaining step S41 includes obtaining a three-dimensional image (suchas, e.g., reading a three-dimensional image of a sacroiliac joint/a SIjoint from a memory). The three-dimensional image may be formed by aplurality of two-dimensional original images (e.g., tomographic orcross-sectional images, which can be visualized as virtual slices), andthe two-dimensional original images may be generated or obtained throughscanning along at least one cutting direction with computed tomography.The three-dimensional image may be a typical three-dimensional data setwhich is a group of two-dimensional slice images acquired by computedtomography and then stored as a computer-readable file which is able topresent internal tissues or organs of a human body on a display.

In accordance with some embodiments, the viewing angle directionselecting step S43 includes selecting a viewing angle direction. Inaccordance with some embodiments of the present disclosure, the imagegenerating step S45 includes generating one or more two-dimensionalimages arranged along the viewing angle direction from thethree-dimensional image. Respective normal directions of the one or moretwo-dimensional images are the same as the viewing angle direction, andeach of the one or more two-dimensional images is inclined to one of acoronal plane, a sagittal plane and an axial plane. In accordance withsome embodiments of the present disclosure, the image superimposing stepS46 includes superimposing the one or more two-dimensional images alongthe viewing angle direction to form a two-dimensional superimposedimage, which is inclined to the one of the coronal plane, the sagittalplane and the axial plane.

In accordance with some embodiments of the present disclosure, theinstrument guiding step S48 includes guiding a movement of the virtualsurgical instrument into the two-dimensional superimposed image, e.g.,real time rendering the virtual surgical instrument in thetwo-dimensional superimposed image according to the position of thesurgical instrument. Therefore, the two-dimensional superimposed imageof the surgical navigation method 40 is advantageous in distinguishingthe position of interest during the surgery. Depending on the viewingangle direction selected, the two-dimensional superimposed image withthe proper viewing angle direction inclined to one of the coronal plane,the sagittal plane and the axial plane can be clearly identified in theimage allowing for an efficient surgical application, e.g., a biologicfusion surgery of a sacroiliac joint by placing a graft material/animplant therein. Medical staff may correctly plan a surgical path andthen implant an instrument, cage and/or graft material in the sacroiliacjoint with the two-dimensional superimposed image. It can greatlyshorten operation time of finding and determining an implantationposition and path, thereby improving safety by reducing the radioexposure and treatment outcomes. The details of the above steps areillustrated in the following 5th and 6th embodiments.

FIG. 9 is a schematic flowchart illustrating a surgical navigationmethod 50 according to the 5th embodiment of the present disclosure.FIG. 10 is a schematic diagram illustrating the guiding of a virtualsurgical instrument 140 using the surgical navigation method 50 of FIG.9 . FIG. 11 is a schematic diagram illustrating superimposition oftwo-dimensional images 126 in an image superimposing step S56 of thesurgical navigation method 50 of FIG. 9 . FIG. 12 is a schematic diagramillustrating selection of a first viewing angle direction DF2 in theviewing angle direction selecting step S53 of the surgical navigationmethod 50 of FIG. 9 . FIG. 13 is a schematic diagram illustrating theselection of the first viewing angle direction DF2 continued from FIG.12 . FIG. 14 is a schematic diagram illustrating a first two-dimensionalsuperimposed image 161, a second two-dimensional superimposed image 162and a third two-dimensional superimposed image 163 in the surgicalnavigation method 50 of FIG. 9 . FIG. 15 is a schematic diagramillustrating a first two-dimensional superimposed image 161 a, a secondtwo-dimensional superimposed image 162 a and a third two-dimensionalsuperimposed image 163 a in the surgical navigation method 50 of FIG. 9. FIG. 16 is a schematic diagram illustrating a surgical navigationsystem 60 according to the 6th embodiment of the present disclosure.

The surgical navigation method 50 of the 5th embodiment is used forguiding the virtual surgical instrument 140 and described with an aid ofthe surgical navigation system 60 shown in FIG. 16 of the 6thembodiment. The virtual surgical instrument 140 may be for example butnot limited to a trocar, drill, cage or graft material. The virtualsurgical instrument 140 may correspond to one surgical instrument 512and may be displayed for the surgeon. The surgical navigation method 50includes an image obtaining step S51, a viewing angle directionselecting step S53, an image generating step S55, an image superimposingstep S56, and an instrument guiding step S58. In accordance with someembodiments, the image obtaining step S51, the viewing angle directionselecting step S53, the image generating step S55, the imagesuperimposing step S56, and the instrument guiding step S58 may beapplied in conjunction with a biologic fusion technique of thesacroiliac joint 560 by placing a graft material/an implant therein,where the virtual surgical instrument 140 is a virtual sheath, and thesurgical instrument 512 is a sheath. However, other virtual surgicalinstruments and surgical instruments may be used.

In accordance with some embodiments of the present disclosure, the imageobtaining step S51 includes obtaining or reading a three-dimensionalimage of a sacroiliac joint 560 (i.e., a three-dimensional sacroiliacjoint image 116) from a memory. The three-dimensional sacroiliac jointimage 116 may be formed and constructed by a plurality oftwo-dimensional original images (e.g., two-dimensional scanned imagessuch as tomographic or cross-sectional images), which may be obtainedthrough scanning along at least one cutting direction such as thedirection from the head to the foot of a patient. In accordance withsome embodiments, the three-dimensional sacroiliac joint image 116 is athree-dimensional medical image generated through scanning of thesacroiliac joint 560 by CT and reconstruction. During CT scanning,specific scanning parameters are used to obtain a required image. Thescanning parameters include a layer thickness and a spacing, where thelayer thickness denotes a section thickness of each two-dimensionaloriginal image, and the spacing denotes a distance between two adjacenttwo-dimensional original images. In other words, each two-dimensionaloriginal image has a layer thickness, and there is a spacing betweenadjacent two of the two-dimensional original images.

In accordance with some embodiments of the present disclosure, theviewing angle direction selecting step S53 includes selecting a viewingangle direction, e.g., a first viewing angle direction DV1 shown in FIG.11 , according to an instruction stored in the memory 360 or aninstruction input from a user interface. In accordance with someembodiments of the present disclosure, the image generating step S55includes generating one or more two-dimensional images 126 arrangedalong the first viewing angle direction DV1 from the three-dimensionalsacroiliac joint image 116, and the first viewing angle direction DV1may be or may not be orthogonal to the cutting direction (the directionof the coronal plane) of the two-dimensional original images during CTscanning.

As shown in FIG. 11 , the three-dimensional sacroiliac joint image 116includes one or more three-dimensional images of a sacrum 561, an ilium562 and the sacroiliac joint 560, and thereby the two-dimensional images126 includes one or more two-dimensional images of the sacrum 561, theilium 562 and the sacroiliac joint 560. Respective normal directions ofthe one or more two-dimensional images 126 are the same as the firstviewing angle direction DV1, and each of the one or more two-dimensionalimages 126 is inclined to one of the coronal plane, the sagittal planeand the axial plane. In accordance with some embodiments of the presentdisclosure, the image superimposing step S56 includes superimposing theone or more two-dimensional images 126 along the first viewing angledirection DV1 to form a two-dimensional superimposed image, e.g., thefirst two-dimensional superimposed image 161 shown in FIG. 14 , which isinclined to the one of the coronal plane, the sagittal plane and theaxial plane.

In accordance with some embodiments of the present disclosure, forbetter placing the cage or graft material in the sacroiliac joint 560for the biologic fusion thereof, the first viewing angle direction DF2in the viewing angle direction selecting step S53 may be selected ordetermined as shown in order from FIG. 12 to FIG. 13 . First, withreference to FIG. 12 , an inclined angle F1 between a normal directionDF1 of a plane PF1 and a normal direction DC1 of a coronal plane P1 of apatient (facing downward in FIG. 12 ) is selected in a range of 30degrees to 35 degrees, and an intersection line (i.e., a rotation axis)between the plane PF1 and the coronal plane P1 is parallel to a normaldirection of the sagittal plane. Next, with reference to FIG. 13 , aninclined angle F2 between the first viewing angle direction DF2 (i.e., anormal direction of a plane PF2) and the normal direction DF1 of theplane PF1 is selected in a range of 20 degrees to 25 degrees, and anintersection line (i.e., a rotation axis) between the plane PF2 and theplane PF1 is parallel to the line representing the plane PF1 shown inFIG. 12 . In another embodiment, the intersection line (i.e., a rotationaxis) between the plane PF2 and the plane PF1 is parallel to the linerepresenting the coronal plane P1 shown in FIG. 12 . In the imagegenerating step S55, one or more two-dimensional images arranged and cutalong the first viewing angle direction DF2 from the three-dimensionalsacroiliac joint image 116 is generated. In the image superimposing stepS56, the one or more two-dimensional images along the first viewingangle direction DF2 are superimposed to form a two-dimensionalsuperimposed image. The one or more two-dimensional images and thetwo-dimensional superimposed image have the same normal directions asthe first viewing angle direction DF2 and are inclined to all thecoronal plane P1, the sagittal plane and the axial plane. In otherwords, there are angles between the two-dimensional superimposed imageand the coronal plane P1, the sagittal plane and the axial plane,respectively. The two-dimensional superimposed image is not parallel toany of the coronal plane P1, the sagittal plane and the axial plane.

In accordance with some embodiments of the present disclosure, theinstrument guiding step S58 includes guiding a movement of the virtualsurgical instrument 140 into first the two-dimensional superimposedimage 161 as shown in FIG. 14 , e.g., real time rendering the virtualsurgical instrument 140 in the first two-dimensional superimposed image161 according to the position of the surgical instrument 512.

The surgical navigation method 50 can be applied to a biologic fusionsurgery of the sacroiliac joint 560. When the surgical navigation method50 is applied thereto, the surgical instrument 512 is a trocar or drillwhich is used in the sacroiliac joint 560 for creating an implantationpathway thereof, and the virtual surgical instrument 140 is a virtualsheath, as shown in FIG. 14 and FIG. 13 .

In the surgical navigation method 50, the viewing angle directionselecting step S53 may further include selecting or determining a secondviewing angle direction, which is orthogonal to the first viewing angledirection DV1; the image generating step S55 may further includegenerating another one or more two-dimensional images arranged along thesecond viewing angle direction from the three-dimensional sacroiliacjoint image 116, respective normal directions of the another one or moretwo-dimensional images are the same as the second viewing angledirection, and each of the another one or more two-dimensional images isinclined to another of the coronal plane, the sagittal plane and theaxial plane; the image superimposing step S56 may further includesuperimposing the another one or more two-dimensional images along thesecond viewing angle direction to form a second two-dimensionalsuperimposed image 162 shown in FIG. 14 , which is inclined to theanother of the coronal plane, the sagittal plane and the axial plane;and the instrument guiding step S58 may further include guiding themovement of the virtual surgical instrument 140 into the secondtwo-dimensional superimposed image 162.

Furthermore, the viewing angle direction selecting step S53 may furtherinclude selecting or determining a third viewing angle direction, whichis orthogonal to the first viewing angle direction DV1 and the secondviewing angle direction; the image generating step S55 may furtherinclude generating further another one or more two-dimensional imagesarranged along the third viewing angle direction from thethree-dimensional sacroiliac joint image 116, and respective normaldirections of the further another one or more two-dimensional images arethe same as the third viewing angle direction; the image superimposingstep S56 may further include superimposing the further another one ormore two-dimensional images along the third viewing angle direction toform a third two-dimensional superimposed image 163 shown in FIG. 14 ;and the instrument guiding step S58 may further include guiding themovement of the virtual surgical instrument 140 into the thirdtwo-dimensional superimposed image 163. Furthermore, when the firstviewing angle direction is selected, the second and third viewing angledirections may be determined without additional selection of inclinedangles with respect to the coronal plane, the sagittal plane or theaxial plane, based on pre-determined conditions and the first, secondand third viewing angle directions being orthogonal to each other.

In accordance with some embodiments of the present disclosure, thefirst, second and third viewing angle directions may be selected inorder, an inclined angle between the first two-dimensional superimposedimage 161 and the coronal plane may be set in a range of 30 degrees to35 degrees, an inclined angle between the second two-dimensionalsuperimposed image 162 and the sagittal plane may be set in a range of20 degrees to 25 degrees, and the third two-dimensional superimposedimage 163 is orthogonal to each of the first two-dimensionalsuperimposed image 161 and the second two-dimensional superimposed image162. With reference to FIG. 11 , the normal direction of the firsttwo-dimensional superimposed image 161 (i.e., the first viewing angledirection DV1) and a normal direction of the coronal plane may be thesame or different. An inclined angle between the normal direction of thefirst two-dimensional superimposed image 161 (i.e., the first viewingangle direction DV1) and the normal direction of the coronal plane is inthe range of 30 degrees to 35 degrees, that is, the inclined anglebetween the first two-dimensional superimposed image 161 and the coronalplane is in the range of 30 degrees to 35 degrees. Specifically, anintersection line between the first two-dimensional superimposed image161 and the coronal plane is parallel to a normal direction of the axialplane, as shown in FIG. 11 . In accordance with some embodiments of thepresent disclosure, the surgical navigation method is not limited forplacing the graft material in the sacroiliac joint. It should beunderstood that any of first, second and third two-dimensionalsuperimposed images can be denominated to have an inclined angle withrespect to and correspond to any of a coronal plane, a sagittal planeand an axial plane, and when any two of the first, second and thirdviewing angle directions are selected, the last one thereof can bedetermined based on the first, second and third viewing angle directionsbeing orthogonal to each other.

Moreover, the first two-dimensional superimposed image 161, the secondtwo-dimensional superimposed image 162 and the third two-dimensionalsuperimposed image 163 can be displayed on a display device 700, asshown in FIG. 14 .

Comparing to the conventional biologic fusion surgery of the sacroiliacjoint, the surgery proceeded only with an aid of a two-dimensionalcaptured image is hard to determine the position for placing a graftmaterial. However, the biologic fusion surgery of the sacroiliac joint560 with an aid of the surgical navigation method 50 according to thepresent disclosure is advantageous in more accurately determine thepathway and/or position (e.g., the position of a teardrop superimposedimage 169 in the first two-dimensional superimposed image 161 shown inFIG. 12 ) for docking, drilling, and placing the cage and/or graftmaterial in the sacroiliac joint 560 by the surgical instrument 512.

With reference to FIG. 9 , FIG. 14 and FIG. 15 , the surgical navigationmethod 50 may further include a step S59. In the step S59, if any of thefirst viewing angle direction DV1, the second viewing angle directionand the third viewing angle direction corresponding to FIG. 12 isrequired to be changed for more assisting the surgery of placing thegraft material in the sacroiliac joint 560, it is determined to returnto the viewing angle direction selecting step S53 for selecting anotherset of the first, second and third viewing angle directions, which areorthogonal to each other. Next, the image generating step S55 and theimage superimposing step S56 are performed to form the firsttwo-dimensional superimposed image 161 a, the second two-dimensionalsuperimposed image 162 a and the third two-dimensional superimposedimage 163 a, as shown in FIG. 15 . For example, the first, second andthird viewing angle directions respectively corresponding to the firsttwo-dimensional superimposed image 161 a, the second two-dimensionalsuperimposed image 162 a and the third two-dimensional superimposedimage 163 a shown in FIG. 15 can be selected according to the previousfirst two-dimensional superimposed image 161, the previous secondtwo-dimensional superimposed image 162 and the previous thirdtwo-dimensional superimposed image 163 shown in FIG. 14 , displayed onthe display device 700. In the step S59, if it is not required, it isdetermined to stay in the instrument guiding step S58 to continue tocooperate by the instrument module 510, the sacroiliac joint opticalsensing apparatus 526 and the virtual surgical instrument 140.

With reference to FIG. 16 , the surgical navigation system 60 accordingto the 6th embodiment of the present disclosure is configured to guidethe virtual surgical instrument 140 and includes a memory 360, aprocessor 460, an instrument module 510, a sacroiliac joint opticalsensing apparatus 526, an optical tracker 600, and a display device 700.

Although not shown, the various components of the surgical navigationsystem 60 need not be fully contained within the user device/equipment.Each of the components may be physically separated from another and morethan one of the components may be used to perform methods consistentwith the present disclosure. Even though the components may bephysically separated, the components may still be communicably connectedby means of wired or wireless technology. For example, differentcomponents of the surgical navigation system 60 and user device may beconnected through the Internet, a LAN (local area network), a WAN (widearea network), databases, servers, RF (radio frequency) signals,cellular technology, Ethernet, telephone, “TCP/IP” (transmission controlprotocol/internet protocol), and any other electronic communicationformat.

In accordance with some embodiments of the present disclosure, thememory 360 is configured to store and access the three-dimensionalsacroiliac joint image 116, where the three-dimensional sacroiliac jointimage 116 is a three-dimensional medical image formed by thetwo-dimensional original images through scanning of the sacroiliac joint560 by CT, and the two-dimensional original images are obtained throughscanning along at least one cutting direction. The memory 360 mayinclude any form of computer-readable storage mediums such asnon-volatile or volatile memories including, by way of example,semiconductor memory devices, such as EPROM, RAM, ROM, DRAM, EEPROM, andflash memory devices; magnetic disks such as internal hard disks andremovable disks; magneto-optical disks; DVD disks, and CD-ROM disks.Memory 360 may be used to store instructions or commands of programcodes.

In accordance with some embodiments of the present disclosure, theprocessor 460 (i.e., a controller, a computing processing apparatus,etc.) is electrically connected to the memory 360, where the processor460 receives the three-dimensional sacroiliac joint image 116 and isconfigured to perform operations including the following steps: theimage obtaining step S41/S51, the viewing angle direction selecting stepS43/S53, the image generating step S45/S55, the image superimposing stepS46/S56, and the instrument guiding step S48/S58 of the 4th/5thembodiment described above and shown in FIG. 8 to FIG. 15 .

In accordance with some embodiments of the present disclosure, theinstrument module 510 includes the surgical instrument 512 and thesurgical instrument optical sensing apparatus 514, where the surgicalinstrument 512 is controlled and displaced by medical staff. Thesurgical instrument optical sensing apparatus 514 may be disposed on thesurgical instrument 512, and includes a reflective ball and a fixingframe, and the fixing frame may be located between the reflective balland the surgical instrument 512. The surgical instrument 512 may be asheath or another surgical instrument, depending on the selection ofmedical staff and use conditions. The sacroiliac joint optical sensingapparatus 526 may be disposed around the sacroiliac joint 560 andincludes a reflective ball and a fixing frame. The fixing frame may belocated between the reflective ball and the sacroiliac joint 560.

The optical tracker 600 may be electrically connected to the processor460 and configured to track the sacroiliac joint 560 and the surgicalinstrument 512 around an anatomical region of a patient, and assist toenhance the accuracy of the virtual surgical instrument 140. When themedical staff controls the surgical instrument 512, the surgicalinstrument optical sensing apparatus 514 may be facing to the opticaltracker 600, so that the optical tracker 600 can track the surgicalinstrument 512 in real time. In addition, the sacroiliac joint opticalsensing apparatus 526 may also be facing to the optical tracker 600, sothat the optical tracker 600 can track the sacroiliac joint 560 in realtime. In detail, the processor 460 is further configured to receive asurgical instrument tracking signal and an anatomical region trackingsignal from the optical tracker 600; and send instructions to thedisplay device 700 to display the virtual surgical instrument 140 on thefirst two-dimensional superimposed image 161/161 a, the secondtwo-dimensional superimposed image 162/162 a and the thirdtwo-dimensional superimposed image 163/163 a shown in FIG. 14 /15, thevirtual surgical instrument 140 positioned and oriented with respect tothe anatomical region in a manner corresponding to a position andorientation of the surgical instrument 512 with respect to theanatomical region.

In accordance with some embodiments of the present disclosure, thedisplay device 700 may be electrically connected to the processor 460,and displays a screen picture, and the screen picture presents a set ofthe first two-dimensional superimposed image 161, the secondtwo-dimensional superimposed image 162 and the third two-dimensionalsuperimposed image 163 shown in FIG. 12 , or another set of the firsttwo-dimensional superimposed image 161 a, the second two-dimensionalsuperimposed image 162 a and the third two-dimensional superimposedimage 163 a shown in FIG. 13 , or any set of the first, second and thirdtwo-dimensional superimposed images orthogonal to each other. Thedisplay device 700 may be any conventional user interface displaydevice. For example, the display device 700 may include computermonitors, televisions, and LCD displays. The display device 700 maydisplay GUI which allows a user to interact with the hardware andsoftware applications of the surgical navigation system 60.

Although the present disclosure has been described in considerabledetail with reference to certain embodiments thereof, other embodimentsare possible. Therefore, the spirit and scope of the appended claimsshould not be limited to the description of the embodiments containedherein. It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A surgical navigation method comprising steps of:obtaining a three-dimensional image; selecting a viewing angledirection; generating one or more two-dimensional images arranged alongthe viewing angle direction from the three-dimensional image;superimposing the one or more two-dimensional images along the viewingangle direction to form a two-dimensional superimposed image; andguiding a movement of a virtual surgical instrument into thetwo-dimensional superimposed image.
 2. The surgical navigation method ofclaim 1, wherein the three-dimensional image is a computed tomographyscan.
 3. The surgical navigation method of claim 1, wherein the one ormore two-dimensional images includes one or more images of a sacrum, anilium and a sacroiliac joint.
 4. The surgical navigation method of claim1, wherein respective normal directions of the one or moretwo-dimensional images are the same as the viewing angle direction. 5.The surgical navigation method of claim 4, wherein each of the one ormore two-dimensional images is inclined to one of a sagittal plane, acoronal plane and an axial plane, and the two-dimensional superimposedimage is inclined to the one of the sagittal plane, the coronal planeand the axial plane.
 6. The surgical navigation method of claim 5,wherein the two-dimensional superimposed image is a firsttwo-dimensional superimposed image, the viewing angle direction is afirst viewing angle direction, and the surgical navigation methodfurther comprises: selecting a second viewing angle direction, which isorthogonal to the first viewing angle direction; generating another oneor more two-dimensional images arranged along the second viewing angledirection from the three-dimensional image, wherein respective normaldirections of the another one or more two-dimensional images are thesame as the second viewing angle direction, and each of the another oneor more two-dimensional images is inclined to another of the sagittalplane, the coronal plane and the axial plane; superimposing the anotherone or more two-dimensional images along the second viewing angledirection to form a second two-dimensional superimposed image, which isinclined to the another of the coronal plane, the sagittal plane and theaxial plane; and guiding the movement of the virtual surgical instrumentinto the second two-dimensional superimposed image.
 7. The surgicalnavigation method of claim 6, further comprising: selecting a thirdviewing angle direction, which is orthogonal to the first viewing angledirection and the second viewing angle direction; generating furtheranother one or more two-dimensional images arranged along the thirdviewing angle direction from the three-dimensional image, whereinrespective normal directions of the further another one or moretwo-dimensional images are the same as the third viewing angledirection; superimposing the further another one or more two-dimensionalimages along the third viewing angle direction to form a thirdtwo-dimensional superimposed image; and guiding the movement of thevirtual surgical instrument into the third two-dimensional superimposedimage.
 8. The surgical navigation method of claim 7, wherein an inclinedangle between the first two-dimensional superimposed image and thecoronal plane is in a range of 30 degrees to 35 degrees.
 9. The surgicalnavigation method of claim 8, wherein an inclined angle between thesecond two-dimensional superimposed image and the sagittal plane is in arange of 20 degrees to 25 degrees.
 10. The surgical navigation method ofclaim 7, wherein the first, second, and/or third two-dimensionalsuperimposed images are displayed on a display device.
 11. The surgicalnavigation method of claim 10, wherein the first, second and thirdviewing angle directions are selected according to a previous firsttwo-dimensional superimposed image, a previous second two-dimensionalsuperimposed image, and a previous third two-dimensional superimposedimage displayed on the display device.
 12. A surgical navigation system,comprising: a memory configured to store a three-dimensional image; acontroller configured to: select a viewing angle direction according toan instruction; generate one or more two-dimensional images arrangedalong the viewing angle direction from the three-dimensional image;superimpose the one or more two-dimensional images along the viewingangle direction to form a two-dimensional superimposed image; and guidea virtual surgical instrument into the two-dimensional superimposedimage; and a display device configured to display the two-dimensionalsuperimposed image.
 13. The surgical navigation system of claim 12,wherein the two-dimensional superimposed image includes one or moreimages of a sacrum, an ilium and a sacroiliac joint.
 14. The surgicalnavigation system of claim 12, wherein respective normal directions ofthe one or more two-dimensional images are the same as the viewing angledirection.
 15. The surgical navigation system of claim 14, wherein eachof the one or more two-dimensional images is inclined to one of acoronal plane, a sagittal plane and an axial plane, and thetwo-dimensional superimposed image is inclined to the one of the coronalplane, the sagittal plane and the axial plane.
 16. The surgicalnavigation system of claim 15, wherein the two-dimensional superimposedimage is a first two-dimensional superimposed image, the viewing angledirection is a first viewing angle direction; and the controller isfurther configured to: select a second viewing angle direction accordingto the instruction, wherein the second viewing angle direction isorthogonal to the first viewing angle direction; generate another one ormore two-dimensional images arranged along the second viewing angledirection from the three-dimensional image, wherein respective normaldirections of the another one or more two-dimensional images are thesame as the second viewing angle direction, and each of the another oneor more two-dimensional images is inclined to another of the coronalplane, the sagittal plane and the axial plane; superimpose the anotherone or more two-dimensional images along the second viewing angledirection to form a second two-dimensional superimposed image, which isinclined to the another of the coronal plane, the sagittal plane and theaxial plane; and guide a virtual surgical instrument into the secondtwo-dimensional superimposed image.
 17. The surgical navigation systemof claim 16, wherein the controller is further configured to: select athird viewing angle direction, which is orthogonal to the first viewingangle direction and the second viewing angle direction; generate furtheranother one or more two-dimensional images arranged along the thirdviewing angle direction from the three-dimensional image, whereinrespective normal directions of the further another one or moretwo-dimensional images are the same as the third viewing angledirection; superimpose the further another one or more two-dimensionalimages along the third viewing angle direction to form a thirdtwo-dimensional superimposed image; and guide the virtual surgicalinstrument into the third two-dimensional superimposed image.
 18. Thesurgical navigation system of claim 17, wherein an inclined anglebetween the first two-dimensional superimposed image and the coronalplane is in a range of 30 degrees to 35 degrees.
 19. The surgicalnavigation system of claim 18, wherein an inclined angle between thesecond two-dimensional superimposed image and the sagittal plane is in arange of 20 degrees to 25 degrees.
 20. The surgical navigation system ofclaim 17, wherein the display device simultaneously displays the first,second, and/or third two-dimensional superimposed images.
 21. Thesurgical navigation system of claim 20, wherein the instruction of thefirst, second and third viewing angle directions are provided accordingto a previous first two-dimensional superimposed image, a previoussecond two-dimensional superimposed image, and a previous thirdtwo-dimensional superimposed image displayed on the display device. 22.The surgical navigation system of claim 12, further comprising: anoptical tracker configured to track the virtual surgical instrument andan anatomical region of a patient; wherein the controller is furtherconfigured to: receive a surgical instrument tracking signal and ananatomical region tracking signal from the optical tracker; and sendinstructions to the display device to display the virtual surgicalinstrument on the two-dimensional superimposed image, the virtualsurgical instrument positioned and oriented with respect to theanatomical region in a manner corresponding to a position andorientation of a surgical instrument with respect to the anatomicalregion.
 23. A computer-readable storage medium, comprising instructions,which when executed on a processor causes the processor to perform asurgical navigational method, the surgical navigational methodcomprising steps of: obtaining a three-dimensional image; selecting aviewing angle direction according to an instruction; generating one ormore two-dimensional images arranged along the viewing angle directionfrom the three-dimensional image; superimposing the two-dimensionalimages along the viewing angle direction to form a two-dimensionalsuperimposed image; and guiding a movement of a virtual surgicalinstrument into the two-dimensional superimposed image.